Why does radiation therapy make feel sick?

Radiation therapy may cause nausea or vomiting due to acute toxicities that may appear during treatment. Vomiting is observed especially during:

1 – ENT irradiation(oral cavity and pharynx), thoracic irradiation (esophagus), or abdominal irradiation (stomach or duodenum) due to inflammation of the mucous membranes (mucositis) through which the food passes

2 – Brain irradiation due to intracranial hypertension caused by the inflammation around the lesions.

Nausea/vomiting can be easily managed with anti-nausea drugs.